The onslaught will never end; they are the Zerg
For all the losses we've been watching Russia take, it's only been about 10% of the forces they sent in. It's inevitable that they'll overwhelm and take the country. At an insanely high cost of course - literally ruining their own country - but it will happen without NATO stepping in, or someone overthrowing the villain (it's surreal to use that term literally). And then they have to try to occupy which will lead to even more casualties